The present invention relates to a switch device, and in particular, to a switch device including a switch operated to drive a device mounted on a subject, a security system, and a switch operation method.
To prevent vehicles from being stolen, portable devices, which transmit an ID code signal including an ID code, have recently been used instead of conventional mechanical keys. Such a portable device is held by an owner (driver) of a vehicle. A “smart ignition” function has been proposed, which enables the engine of a vehicle to be started based on an ID code signal wirelessly transmitted from the portable device. As one example, Japanese Laid-Open Patent Publication No. 2002-188505 describes an engine controller for vehicles with the smart ignition function.
In a vehicle with the smart ignition function, for example, a push-button ignition switch and a portable device slot, into which a portable device is inserted, are installed on the instrument panel in the passenger compartment. Normally, the portable device, held, for example, in a pocket of the owner's clothing, mutually communicates with the vehicle by automatically transmitting an ID code signal to the vehicle. The vehicle enables its engine to start on the condition that an ID code included in the ID code signal transmitted from the portable device matches an ID code preset for the vehicle. When the owner presses the ignition switch in this state, a starter motor is driven to start the engine of the vehicle.
When the portable device does not automatically transmit the ID code signal due to, for example, voltage decrease of its battery, the owner can use the portable device slot to start the engine. In more detail, the owner inserts the portable device in the portable device slot so that a transponder in the portable device receives a driving radio wave transmitted from the portable device slot. The transponder then supplies the vehicle with a transponder signal including an ID code for the transponder (transponder code). The vehicle compares the transponder code with the ID code of the vehicle.
As described above, the portable device slot installed in the passenger compartment of the vehicle is not normally used but is used only in an emergency such as when the battery of the portable device is drained. Nevertheless, sufficient space for the portable device slot, which has a holding mechanism for holding the portable device, needs to be provided in the vehicle. In recent years, however, vehicle systems have been rapidly computerized and have become provided with more functions. This has increased the number of electric and electronic components used in vehicles. Thus, it has become extremely difficult to provide sufficient space for the portable device slot within the limited space of the vehicle. Further, the portable device slot is composed of a large number of components including the portable device holding mechanism and a coil antenna, which outputs a transponder-driving radio wave. This increases the manufacturing cost of a device with the smart ignition function.